Photocell Economic History

Katy Ashe
November 25, 2010

Fig. 1: Maximum Efficiencies of
Photovoltaic Cells over the Past Six Decades. [2,4]

Solar energy conversion technology if viable could
completely revolutionize the power sector throughout the world. The
amount of solar energy that strikes the Earth in an hour is more than
enough energy to meet the solar demands of the global population for an
entire year. [1] It is facts like this that continue to make improving
this technology so alluring. The potential is incredible, but there are
many barriers that prevent solar photovoltaic cells from contributing as
a major source of global electricity generation. Solar photovoltaic
cells have existed since 1954 and this technology has dramatically
changed over time. [2] As energy collection efficiency has increased and
the costs of manufacturing have decreased this technology has found
different niches over the past several decades. [2] As the world
searches for sources of carbon-neutral electricity generation it would
be nice to have solar energy make-up part of the solution because of the
large, widely accessible source of solar energy. Yet, in order for solar
power to become a major source of world electrical energy it must become
more cost-effectively captured, converted and stored. [3]

A Quick History of Solar Photovoltaics

In 1954 photovoltaic technology was created by Daryl
Chapin, Calvin Fuller, and Gerald Pearson at Bell Labs in the US. [2]
This original cell had an efficiency of 4%, but this same style of
silicon solar cell later achieved and efficiency of 11%. [2] The solar
technology was utilized in its early years as a source of electricity
for small office supplies that only required small amounts of
electricity. [2] Yet, for the most part the attempt to commercialize
solar cells in the 1950s and 60s was a failure. [2] They were too
expensive and inefficient to provide much practicality for most domestic
applications. However, in 1958 the Vanguard I, Explorer III, Vanguard
II, and Sputnik-3 satellites were all launched with photovoltaic cells
onboard as the powering energy source. [2] Solar photovoltaic cells are
still the accepted energy source for satellites today. [2]

Then, in the 1970s Dr. Elliot Berman of the Exxon
Corporation designed a solar cell that could produce electricity at $20
per watt versus the previous rate of $100 per watt. [2] Suddenly, solar
technology became practical for technologies other than satellites.
Photovoltaic cells began powering navigation warning lights, horns on
offshore oil rigs, lighthouses, railroad crossings, and many small
domestic applications. [2] Photovoltaics became present in households
where connection to the traditional electricity grid was not
affordable.

In 1982 the first photovoltaic megawatt power station
was opened in Hisperia, California. [2] The push to create photovoltaic
power across the world in the past thirty years has increasingly focused
of domestic integration. In 1993 Pacific Gas and Electric started the
first grid-supported photovoltaic system. [2] This was just one of many
attempts at experimenting with solar electricity generation as a
mainstream concept. In the 2000s many companies had begun focusing on
large-scale manufacturing of solar panels in order to reduce cost. [2]
Yet, the despite the industries best efforts this technology is still
not a mainstream success. Throughout the past several decades the
efficiency of photovoltaic cells has greatly increased, but domestic
integration of this technology has not become feasibly on a large
scale.

The Future Feasibility of Photovoltaics

Why is this technology currently not feasible? The
technology existing for efficiency of solar photovoltaic systems has
surpassed the expected limit of efficiency predicted with the
Shockley-Queisser efficiency limit. [3] The science behind creating
efficient solar panels is excellent at this point in time, so the main
issue with feasibility of this technology is cost. The future of this
technology is dependent upon low-cost developments in the manufacturing
of capture, conversion, and storage of sunlight. [3] The PV modules that
are currently shipped and used domestically have an efficiency of
approximately 20% and cost about $300 per square meter. [3] Notice how
the efficiency of this system is significantly less than the most
efficient technology that currently exists. This is because it is
significantly less expensive to produce solar panels with this lower
efficiency, which reiterates that manufacturing price rather than
efficiency of solar panels is the limiting factor to the growth of this
technology. [3] In order to recover the initial capital investment for a
solar panel with this efficiency over the lifetime power generation
costs must be $0.25 to $0.30 per kilowatt-hour. [3] Unfortunately, the
current cost of electricity from utilities is around $0.03 to $0.05.
[3]

The reason the purity is the main constraint for
manufacturing technologies lies in the cost-thickness-purity constrain
of a solar cell. [3] As a solar cell becomes thicker we are capable of
collecting more incident sunlight. [3] However, with a thicker layer a
higher purity of material is required. This is because impurities cause
shortened lifetimes of photo-excited charge carriers. [3] Thus, with an
impure material the layer needs to be thinner in order for a charge to
be transmitted to the electrical junction, but the thinner layer will
allow for less collection of incident sunlight. [4] In order to reduce
the cost of the production of PV modules the cost-thickness-purity
relationship needs to be improved and maximized. [3] As photovoltaic
technology moves forward much attention will be focused on the low-cost
production of high purity materials.